Honestly, if this question's asking about type matchups, I think it's too ambiguous to answer; the wording makes me think that the OP wants an analysis like "grass may have the most weaknesses of any type, but it is also one of the only 3 types with a ground resistance, so it's a good type" or something like that, rather than just which type has the most resistances, and I feel like trying to find the "most important resistances" like this will branch out into an open discussion without a definitive answer, which is against the rules.
I'll hold off on flagging the question until some clarification is given, though.